the planck view of cmb contamination from diffuse foregrounds

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The Planck view of CMB Contamination from Diffuse Foregrounds

Carlo BaccigalupiOn Behalf of the Planck CollaborationKITP Conference, April 2013

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● Component Separation for Planck● CMB solutions● Consistency and Robustness● Cosmology from Component Separation ● Diffuse Foregrounds● Conclusions

The Planck Collaboration XII

Outline

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Outline

Contribution from Jean-Francois Cardoso

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Outline

See Graca's talk

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Outline

Thanx to Ingunn and the C-R team

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OutlineT

he Planck C

omponent S

eparation Group

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Component separation for Planck


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Component Separation for Planck

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Component Separation for PlanckYour data The mixing matrix

CMB and foregrounds

Noise

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Component Separation for Planck

components

frequencies

components

resolution elements

resolution elements

frequencies

frequencies

resolution elements

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● Know nothing● Know something


On foregrounds you...

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● Look for minimum variance ● Model and fit


Thus you...

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● Look for minimum variance 1 in the needlet (spherical wavelet) domain – NILC

2 in the pixel domain – SEVEM

● Model and fit 3 semi-parametrically in the harmonic domain – SMICA

4 physical parameters in the pixel domain – C-R


And you...

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● Look for minimum variance 1 in the needlet (spherical wavelet) domain

2 in the pixel domain

● Model and fit 3 semi-parametrically in the harmonic domain

4 physical parameters in the pixel domain


And you...

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CMB solutions

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● Parallel runs on data and Full Focal Plane (FFP6) simulations, including the best in flight knowledge of instrumental behavior

● Instrumental error is propagated through noise variance (and covariance at low l for C-R for use in the likelihood) as well as through half-ring differences

● The beam is evaluated through ...

● Quantitative claims on:

● auto-spectra, cosmological parameter estimation

● Primordial Non-Gaussianity

● Lensing


Characterization of the CMB solutions

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● 2013 paper where component separation products were used for quantitative statements:

● Planck 2013, I, overview

● Planck 2013, XI, consistency

● Planck 2013 XIII, CO

● Planck 2013 XV, likelihood

● Planck 2013 XVI, cosmological parameters

● Planck 2013 XVII, lensing

● Planck 2013 XIX, ISW

● Planck 2013 XXIII, Isotropy

● Planck 2013 XXIV, non-Gaussianity

● Planck 2013 XXV, cosmic strings

● Planck 2013 XXVI, topology

● ...The Planck Collaboration XII

CMB solutions and Planck papers

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CMB solutions differences

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CMB standard deviation evaluated over methodology

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The Planck Collaboration XII; Courtesy of Jean-Francois Cardoso

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Highlights on Component Separation: Spectral Matching

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● Localization in the pixel and harmonic domain (needlets) allows to treat foregrounds differently depending on their intensity in different regions of the sky and the angular domain

● Reducing to channel coaddition when they are absent, typically at small angular scales


Highlights on Component Separation: Spatial and Spectral Localization

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Consistency and Robustness


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Sky masks

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Sky masks

● Threshold maskings is made by combining 30 and 353 Ghz flux thresholding for achieving a given sky fraction

● Confidence masks are method dependent: ● C-R

● NILC

● SEVEM

● SMICA

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Pseudo-spectra

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Pseudo-spectra

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Null tests on FFP6: foreground residuals

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Null tests on FFP6: lensing

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Cosmology from Component Separation


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● See forthcoming Graca's talk on power spectra and cosmological parameter estimation

● Paul and Ben's talks on primordial non-Gaussianity

● Duncan's talk on lensing extraction

● Full list:

● Planck 2013 XV, likelihood

● Planck 2013 XVI, cosmological parameters

● Planck 2013 XVII, lensing

● Planck 2013 XIX, ISW

● Planck 2013 XXIII, Isotropy

● Planck 2013 XXIV, non-Gaussianity

● Planck 2013 XXV, cosmic strings

● Planck 2013 XXVI, topology


Cosmology with Component Separation

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● A leap forward for Component Separation in Planck

● Likely to split from now on into specialized foreground cleaning for CMB extraction, and foreground reconstruction for astrophysical studies

● CMB solutions from a complete set of approaches are consistent on a large sky fraction, at the level of the two and three point statistics

● Cosmological parameters from auto-spectra are consistent with the cross-spectra likelihood (see Graca's talk)

● Primordial non-Gaussianity and lensing results are consistent (see Paul's, Ben's and Duncan's talks monday)

● At low latitudes, relevant differences persist

● Simulations enable us to isolate the solution with the lowest residual contamination from diffuse foregrounds


Conclusions: CMB

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Diffuse Foregrounds


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● Planck adopts a pixel based parametric approach for separating diffuse foregrounds

● Parameters in the pixel domain: spatially varying spectral indices and amplitudes of foreground components

● Fitting procedure: Markov Chains Monte Carlo over the multi-frequency datasets

● Main references: Brandt et al. 1994 (main idea), Eriksen et al. 2006 (efficient fitting through Gibbs sampling), Eriksen et al. 2008 (Jeffrey’s prior is introduced), Stompor et al. 2009 (high resolution fitting on the basis of chains conducted at low resolution)

● Implementation in the Commander-Ruler code which was used for all results presented in the Planck XII paper


Recovery of diffuse foregrounds with Planck

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● Low frequency amplitude at 30 GHz and spectral index, effectively describing a mixture of various astrophysical effects, as Brehmsstrahlung (free-free), Anomalous Dust Emission (AME), Synchrotron

● CO amplitude at 100 GHz● Thermal Dust amplitude at 353 GHz and grey body

temperature and emissivity ● Monopoles and dipoles over the frequency channels

which are considered for separation, to be estimated separately, at low resolution (Wehus et al. 2013)


Foreground model

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● Inputs: Planck sky maps, 30-353 GHz, total and half-ring datasets along with their characterization

● Spectral indices estimation at low resolution takes as inputs the maps are smoothed to 40 arcminutes common resolution, re-pixelized at Nside=256

● Mixing matrices are applied to the Ruler resolution dataset corresponding to 7.1 arcminutes


Methodology

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From Commander to Ruler

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● Amplitude and spectral index of the low frequency component as seen by Planck

● Different emission mechanism, such as Brehmstraalung, synchrotron and low frequency dust emission are reflected in the sky distribution of the spectral index


The Planck low frequency foregrounds

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● Planck is sensitive to 9 CO transition lines in its frequency range

● Fit is done by modeling the emission is modelled as a constant line ratio over the full sky for increasing signal to noise ratio, isolate regions heavily affected by this emission


CO emission as seen by Planck

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● Planck provides an exquisite mapping of the Galactic thermal from 100 to 857 Ghz

● Planck resolves the sky pattern of dust emissivity, reflecting different phases in the interstellar gas


The Planck view of thermal dust

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● A comparison is made between the dust solution in the frequency interval where the fit is done and the dust dominated channels at 545, 857 Ghz

● A scatter plot reveals substantial agreement in the common 353 Ghz channel


The Planck view of thermal dust

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Validating on FFP6...

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● Planck is able to separate diffuse Galactic foregrounds on 87% of the sky, quantifying uncertainties from the separation procedure as well as instrumental noise

● Planck resolves a single low frequency component amplitude and effective spectral index, CO line ratio, and a thermal dust amplitude and emissivity

● An extensive study involving other datasets is necessary for fully exploit the Planck capability of studying the astrophysical properties of foregrounds, in particular at low frequencies


Conclusions: foregrounds

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● Over the next year we plan to...● Say goodbye to Component Separation doing

everything, welcome specialization for CMB extraction and foreground recovery

● Extracting Foregrounds using Ancillary Datasets● Use more data, 2.5 years versus 1● Continuing to study systematics, beam effect at

arcminute resolution in particular● Polarization...● ...


What's next

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● Beams transfer functions are provided

● NILC, SEVEM, SMICA adopt a Gaussian representation of the beam with 5 arcminutes FWHM

● C-R esimates the beam transfer function though FFP6 Mcs adopting in flight main beam measurements


Beams

the planck view of cmb contamination from diffuse foregrounds

Documents

planck collaboration

likelihood planck

lensing planck

isotropy planck

isw planck

overview planck

cosmological parameters

nongaussianity planck